Chandra observation of the fast X-ray transient IGR J17544-2619: evidence for a neutron star?

By J. I. Zand. 2005

154 citations recorded by the source corpus.

IGR J17544-2619 belongs to a distinct group of at least seven fast X-ray transients that cannot readily be associated with nearby flare stars or pre-main sequence stars and most probably are X-ray binaries with wind accretion. Sofar, the nature of the accretor has been determined in only one case (SAX J1819.3-2525/V4641 Sgr). We carried out a 20 ks Chandra ACIS-S observation of IGR J17544-2619 which shows the source in quiescence going into outburst. The Chandra position confirms the previous tentative identification of the optical counterpart, a blue O9Ib supergiant at 3 to 4 kpc (Pellizza, Chaty & Negueruela, in prep.). This is the first detection of a fast X-ray transient in quiescence. The quiescent spectrum is very soft. The photon index of $5.9\pm1.2$ (90% confidence error margin) is much softer than 6 quiescent black hole candidates that were observed with Chandra ACIS-S (Kong et al. 2002, ApJ, 570, 277; Tomsick et al. 2003, ApJ, 599, L133). Assuming that a significant fraction of the quiescent photons comes from the accretor and not the donor star, we infer that the accretor probably is a neutron star. A fit to the quiescent spectrum of the neutron star atmosphere model developed by Pavlov et al. (1994, A&A, 289, 837) and Zavlin et al. (1996, A&A, 315, 141) implies an unabsorbed quiescent 0.5–10 keV luminosity of $(5.2\pm1.3)\times10^{32}$ erg s -1 . We speculate on the nature of the brief outbursts.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6c7db2339027c2d5f5f2219e3e57b515f375c3cf

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In Astronomy and Astrophysics

1. S. Tsygankov
2. M. Falanga
3. E. Bozzo
4. L. Stella
5. A. Lutovinov
6. Roland Walter

In Instrumentation

1. S. Tsygankov
2. E. Bozzo
3. A. Lutovinov
4. Roland Walter

Citations in the corpus

• High-mass X-ray binaries in the Milky Way (2013, background): “IGRJ16320-4751 is a persistent source (in ’t Zand et al., 2003) serendipitously discovered with INTEGRAL (Tomsick et al., 2003).”
• Catalogue of high-mass X-ray binaries in the Galaxy (4th edition) (2006, unknown): “1 − 2733 (Sakano et al. 2002, see in’t Zand 2005) and XTE J1901 + 014 (Remillard & Smith 2002), together with 8 other members (XTE J1739-302, IGR J17544-2619, IGR J16465-4507, AX 1845.0-0433, AX J1841.”
• Probing clumpy stellar winds with a neutron star (2007, background): “The SFXT behavior is best explained by the interaction between the accreting compact object and a clumpy stellar wind (in’t Zand 2005; Leyder et al. 2007).”
• INTEGRAL/IBIS all-sky survey in hard X-rays (2007, unknown): “…et al. (2005a), (26) Bykov et al. (2004), (27) Bassani et al. (2005), (29) Pavlinskii et al. (1992), (30) Lutovinov et al. (2003c), (31) in’t Zand (2005), (32) Bikmaev et al. (2006a), (33) Negueruela & Smith (2006), (34) Produit et al. (2003), (35) Barlow et al. (2005), (36) Barlow et al.…”
• Are There Magnetars in High-Mass X-Ray Binaries? The Case of Supergiant Fast X-Ray Transients (2008, background): “Several authors (In’t Zand 2005; Leyder et al. 2007; Walter & Zurita Heras 2007) suggested the presence of dense clumps in the wind of the OB companions in order to attain the luminosity variations of SFXTs.”
• Unveiling Supergiant Fast X-Ray Transient Sources with INTEGRAL (2006, methodology): “Chandra observed the source both in quiescence and outburst on 3 July 2004 (in't Zand 2005), the luminosity (0.5–10 keV) in quiescence is ∼ 5×10 32 erg s −1 while the spectrum during the outburst is hard and moderately absorbed. in't Zand (2005) suggests that the accretor is a neutron star.”